Restricted orifice device



Feb. 21, 1933.

. I l l I 11 c. P. HOV.VARD 1,898,537

RESTRICTED ORIFICE DEVICE Filed Nov. 16, 1931 Patented Feb. 21, 1933 UNITED STATES lesser.

PATENT 4am-- OLIFTON P. HOWARD, F. WORCESTER, MASSACHUSETTS, ASSIGNOR T0 ROOKWOOD SPRINKLER COMPANY OF M'ASSACHUSETTS, OF WORCESTER, MASSACHUSETTS, A

CORPORATION OF MASSACHUSETTS nns'rnrornn oiurrcn DEVICE Application filed November 16, 1931. Serial No. 575,357.

- which a restricted flow of air or gas is permitted between different pressure areas. Such devices are commonly used where a retarded-equalization of pressure 1s desired after a change in pressure at one side of the One instance of suchuse is in certain types of air exhausters for dry pipe sprinklersys tems. In such exhausters, an. air pressure chamber is provided which has no outlet except through a restricted orifice and in which the air is normally maintained at dry plpe pressure. l/Vhen a sprinkler head opens, the dry pipe pressure drops quickly, while the pressure in the closed chamber drops much more slowly, due to the restricted orifice through which the air must escape.

The difiierential pressure thus developed is utilized to open a large vent valve through which the remaining airin the dry pipe system may be quickly discharged. Orifice devices of different kinds have been tried in such air exhausters but much difficulty has been encountered, due to the clogging of the orifices by dust or dirt. Fine strainers have been provided to protect the orifice but these strainers also fill up and become clogged in course of time.

It is the object of my invention to provide an improved orifice device for such purposes, so designed that it may be easily and cheaply constructed and that it will be relatively free from the difiiculty of clogging.

A further object is to provide a construction in which two orifice members in series produce the restrictive efiect of a single orifice of substantially less diameter.

My invention further relates to arrange ments and combinations of parts which will be hereinafter described and -more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawing, in which Fig. 1 is a sectional side elevation of portions of. an air-exhauster having my invention embodied therein;

' Fig. 2 is a sectional side elevation of my improved orifice device;

Fig. 8 is a sectional side elevation of one.

of the orifice members;

Fig. 4 is an end elevation thereof, looking in. the direction of the arrow 4 in Fig. 3; Fig.5 is a view similar to Fig. 3 but showing a slight modification, and

Fig. 6 is a sectional elevationshowing a further modification.

Referring to Fig. 1, I have shown a portion of an air eXhauster including a pressure chamber 10, a chamber 11 freely connected to the dry pipe system, a partition 12 separating the chambers 10 and 11 and having an opening 13 therethrough, a diaphragm 14 eX- tending across the chamber 11 below the partition 12, and a member 15 extending through an opening in the center of the diaphragm 14 and securely clamped thereto by a nut16. The member 15 and nut 16 extend freely upward through the opening 13, leaving a substantial airpassage around the nut 16, so

that the air under pressure in the chamber" 10 has direct access to the upperside of the diaphragm 14. 7 g Y My improved orifice device D is mounted in a threaded opening 17 in the upper part of the member 15, which opening 17 is con- 5 v The orifice device D in its preferred form comprises a holder 20 having an end portion 21 to which a wrench may be applied andhaving a hub portion 22 which is externally threaded to engage the'threaded opening 17 in the member 15; The member 20 is also pro vided with an axial passage 24, an annular shoulder 25, an internally threaded portion 26, and an enlarged end recess 27.

Orifice members 30 are mounted in the passage 24 and in a corresponding passage 31 in a clamping screw 32, which is threaded into the portion 26 of the holder 20. -,Tl1e enlarged head of the screw 32 is received in the enlarged recess 27.

The orifice members 30 are provided with end flanges 35 which are clamped against the shoulder 25 by the clamping screw 32, by which means the orifice members are securely held in the holder 20. Each orifice member 30 is also provided with a conical portion 37 projected out of the plane of the flange 35 and having a restricted orifice a0 extending through the extreme pointed end of the conical portion 37.

In the preferred form, the member 30 is of hollow construction, with the flange 35 and conical portion 37 all formed of suitable and relatively thin metal.

hile a single one of the orifice members 30 may be used in the holder 20, I prefer to use these orifice members in pairs, as shown in Fig. 2, as improved results are attained by thus combining two of the members 30.

I have found by experiment that the provision of the orifice d0 at the extreme end of a conical portion, as 37, largely does away with the liability to clogging by small particles of dust or dirt, and that the orifice is very much less liable to clog than is the case where the orifice is made in a fiat metal disc, as has been previously the custom. In fact, the substitution of my improved orifice member or members for the perforated flat metal disc has enabled me to do away entirely with the fine mesh strainers which have been previously used in such devices. 7

Furthermore, I have found that a pair of my improved orifice members, oppositely disposed as shown in Fig. 2, will have the same restricting effect as a single perforated disc having a substantially smaller orifice. For example, the use of two of my improved orifice members with openings of .010" in diameter will produce the same restricting efi'ect as a single plate having an opening of .007 in diameter. Obviously, the larger openings are easier to form' accurately and are less liable to clogging than the smaller opening required to produce the same effect in a single flat plate.

If for any reason my improved orifice members require renewal, the removal and replacement of these members may be effected by any mechanic without special skill or experience, whereas with the previous construction a relatively large unit was necessarily replaced.

In the construction shown in Fig. 5, the walls of the orifice member 50 isprovided with side walls which are gradually reduced in thickness toward the perforated outer end or point, thus presenting a very thin or knife edge effect around the orifice.

In Fig. 6, I have shown the two orifice members, as 30 or 50, secured together by crimping one flange 55 around the other mounted in said holder with said end flanges flange 56, thus preventing separation of the pair of orifice members.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details hereindisclosed, otherwise than as set forth in the claims, but what I claim is 1. A device for effecting very slow air flow between chambers containing air at substantially difierent presures which comprises a holder having an axial opening therethrough, a pair of orifice members reversely mounted within said holder and in said opening and each having an outwardly extended and substantially conical portion with a greatly restricted perforation through its extreme outer pointed end, and means to hold said 7 members reverselymounted in said holder.

2. A device for effecting very slow air flow between chambers containing air at substanthrough, a pair of orifice members reversely mounted within said holder and in said opening and each having an end flange and an outwardly extended and substantially conical portion with a greatly restricted perforation through its extreme outer pointed end, and means to hold said members reversely firmly engaging each other and in said holder.

In testimony whereof I have hereunto affixed my signature.

CLIFTON P. HOWARD.

firmly seated Mo's. 

